nix(feat): Add postgrest-git-hooks to enable pre-commit and pre-push hooks

nix/tools/devTools.nix

@@ -4,6 +4,8 @@
 , checkedShellScript
 , devCabalOptions
 , entr
+, git
+, gnugrep
 , graphviz
 , haskellPackages
 , hsie
@@ -65,23 +67,161 @@ let
         name = "postgrest-check";
         docs =
           ''
-            Run most checks that will also run on CI.
+            Run most checks that will also run on CI, but only against the
+            latest PostgreSQL version.
 
-            This currently excludes the memory tests, as those are particularly
+            This currently excludes the memory and spec-idempotence tests,
-            expensive.
+            as those are particularly expensive.
           '';
         inRootDir = true;
       }
       ''
-        ${withTools.withPgAll} ${tests}/bin/postgrest-test-spec
+        ${tests}/bin/postgrest-test-spec
-        ${withTools.withPgAll} ${tests}/bin/postgrest-test-querycost
+        ${tests}/bin/postgrest-test-querycost
         ${tests}/bin/postgrest-test-doctests
-        ${tests}/bin/postgrest-test-spec-idempotence
         ${tests}/bin/postgrest-test-io
         ${style}/bin/postgrest-lint
         ${style}/bin/postgrest-style-check
       '';
 
+  gitHooks =
+    let
+      name = "postgrest-git-hooks";
+    in
+    checkedShellScript
+      {
+        inherit name;
+        docs =
+          ''
+            Enable or disable git pre-commit and pre-push hooks.
+
+            Basic is faster and will only run:
+              - pre-commit: postgrest-style
+              - pre-push: postgrest-lint
+
+            Full takes a lot more time and will run:
+              - pre-commit: postgrest-style && postgrest-lint
+              - pre-push: postgrest-check
+
+            Changes made by postgrest-style will be staged automatically.
+
+            Example usage:
+              postgrest-git-hooks disable
+              postgrest-git-hooks enable basic
+              postgrest-git-hooks enable full
+
+            The "run" operation and "--hook" argument are only used internally.
+          '';
+        args =
+          [
+            "ARG_POSITIONAL_SINGLE([operation], [Operation])"
+            "ARG_TYPE_GROUP_SET([OPERATION], [OPERATION], [operation], [disable,enable,run])"
+            "ARG_POSITIONAL_SINGLE([mode], [Mode], [basic])"
+            "ARG_TYPE_GROUP_SET([MODE], [MODE], [mode], [basic,full])"
+            "ARG_OPTIONAL_SINGLE([hook], , [Hook], [pre-commit])"
+            "ARG_TYPE_GROUP_SET([HOOK], [HOOK], [hook], [pre-commit,pre-push])"
+          ];
+        positionalCompletion =
+          ''
+            if test "$prev" == "${name}"; then
+              COMPREPLY=( $(compgen -W "enable disable" -- "$cur") )
+            elif test "$prev" == "enable" || test "$prev" == "disable"; then
+              COMPREPLY=( $(compgen -W "basic full" -- "$cur") )
+            fi
+          '';
+        inRootDir = true;
+      }
+      ''
+        if [ run != "$_arg_operation" ]; then
+          # Remove all hooks first and ignore failures because the file might be missing.
+          # This assumes that we're only adding lines that include "postgrest-git-hooks"
+          # to the hook file.
+          sed -i -e '/postgrest-git-hooks/d' .git/hooks/pre-{commit,push} 2> /dev/null || true
+
+          if [ disabled != "$_arg_mode" ]; then
+            # The nix-shell && + nix-shell || pattern makes sure we can run the hook
+            # in a pure nix-shell, where nix-shell itself is not available, too.
+
+            # The $(nix-shell --run "command -v ...") pattern ensures we only need to enable
+            # the hooks once and still run the latest of our hook scripts, even when we
+            # update them in the repo.
+
+            echo 'command -v nix-shell > /dev/null || postgrest-git-hooks --hook=pre-commit run' "$_arg_mode" \
+              >> .git/hooks/pre-commit
+            # shellcheck disable=SC2016
+            echo 'command -v nix-shell > /dev/null && $(nix-shell --quiet -Q --run "command -v postgrest-git-hooks") --hook=pre-commit run' "$_arg_mode" \
+             >> .git/hooks/pre-commit
+            chmod +x .git/hooks/pre-commit
+
+            echo 'command -v nix-shell > /dev/null || postgrest-git-hooks --hook=pre-push run' "$_arg_mode" \
+              >> .git/hooks/pre-push
+            # shellcheck disable=SC2016
+            echo 'command -v nix-shell > /dev/null && $(nix-shell --quiet -Q --run "command -v postgrest-git-hooks") --hook=pre-push run' "$_arg_mode" \
+             >> .git/hooks/pre-push
+            chmod +x .git/hooks/pre-push
+          fi
+        else
+          # When run from a git hook, the GIT_ environment variables conflict with our withGit helper.
+          # The following unsets all GIT_ variables.
+          unset "''${!GIT_@}"
+
+          case "$_arg_mode" in
+            basic)
+              case "$_arg_hook" in
+                pre-commit)
+                  # To be able to automatically add only changes from postgrest-style to the staging area,
+                  # we need to run postgrest-style twice. Otherwise we'd risk merge conflicts when popping
+                  # the stash afterwards.
+                  ${style}/bin/postgrest-style
+
+                  stash="postgrest-git-hooks-$RANDOM"
+                  ${git}/bin/git stash push --include-untracked --keep-index -m "$stash"
+                  if [ "$(git stash list --grep $stash)" ]; then
+                    # Only create the stash pop trap, if we actually created a stash.
+                    # Otherwise stash pop will cause havoc.
+                    trap '${git}/bin/git stash pop $(git stash list --format=format:%gD --grep "$stash" -n1)' EXIT
+                  fi
+
+                  ${style}/bin/postgrest-style
+                  ${git}/bin/git add .
+                  ;;
+                pre-push)
+                  # Create a clean working tree without any uncomitted changes.
+                  ${withTools.withGit} HEAD ${style}/bin/postgrest-lint
+                  ;;
+              esac
+              ;;
+            full)
+              case "$_arg_hook" in
+                pre-commit)
+                  # To be able to automatically add only changes from postgrest-style to the staging area,
+                  # we need to run postgrest-style twice. Otherwise we'd risk merge conflicts when popping
+                  # the stash afterwards.
+                  ${style}/bin/postgrest-style
+
+                  stash="postgrest-git-hooks-$RANDOM"
+                  ${git}/bin/git stash push --include-untracked --keep-index -m "$stash"
+                  if [ "$(git stash list --grep $stash)" ]; then
+                    # Only create the stash pop trap, if we actually created a stash.
+                    # Otherwise stash pop will cause havoc.
+                    trap '${git}/bin/git stash pop $(git stash list --format=format:%gD --grep "$stash" -n1)' EXIT
+                  fi
+
+                  ${style}/bin/postgrest-style
+                  ${git}/bin/git add .
+
+                  ${style}/bin/postgrest-lint
+                  ;;
+                pre-push)
+                  # Create a clean working tree without any uncomitted changes.
+                  ${withTools.withGit} HEAD ${check}
+                  ;;
+              esac
+              ;;
+          esac
+        fi
+      '';
+
   dumpMinimalImports =
     checkedShellScript
       {
@@ -147,6 +287,7 @@ buildToolbox
     watch
     pushCachix
     check
+    gitHooks
     dumpMinimalImports
     hsieMinimalImports
     hsieGraphModules

nix/tools/style.nix

@@ -44,6 +44,8 @@ let
       ''
         ${style}
 
+        trap "echo postgrest-style-check failed. Run postgrest-style to fix issues automatically." ERR
+
         ${git}/bin/git diff-index --exit-code HEAD -- '*.hs' '*.lhs' '*.nix'
       '';